The overall aim of this project is to identify the gene(s) other than HLA that contribute to Graft-versus-host disease (GVHD). The Genetics Core Facility of the GCRC would be utilized for the production of immortalized cell lines from research subjects, as they are identified. Lymphocytes will be immortalized with EBV for the purpose of providing a renewable supply of cells and DNA for analysis. The availability of these lymphoblast cells will facilitate delineation of the specific gene(s).